Note 12 - Shareholders' Equity - Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net Income:
Net income	$ 15,512,000	$ 13,992,000	$ 8,189,000
Earnings Per Share:
Basic earnings per common share (in dollars per share)	$ 3.01	$ 2.74	$ 1.64
Diluted earnings per common share (in dollars per share)	$ 2.97	$ 2.68	$ 1.58
Weighted Average Number of Shares Outstanding:
Basic shares (in shares)	5,155	5,108	5,005
Diluted shares (in shares)	5,228	5,219	5,185